Electromagnetic relay



April 21, 1964 L. O. WOODS ELECTROMAGNETIC RELAY Filed July 5. 1961 3,130,284 ELECTROMAGNETIC RELAY Lee 0. Woods, Morrison, Iil., assignor to General Electric Company, a corporation of New York Filed July 3, 1961, Ser. No. 121,404 '10 Claims. (Cl. 200--111) My invention relates to small electromagnetic relays United States Patent and more particularly to electromagnetic relays used in circuits for energizing small single-phase motors.

An important object of this invention is to provide an improved electromagnetic relay which is capable of efficiently carrying a relatively high current.

Another object of this invention is to provide a relatively inexpensive current relay which is capable of carrying a relatively high current, and includes an improved means to easily compensate for minor variations due to manufacturing tolerances so that the relay may be accurately calibrated to have the desired pick-up characteristic.

It is a still further object of this invention to provide an improved relay structure which is compact, dependable in use, and economical to manufacture.

- Another object of my invention is to provide an improved method for manufacturing an electromagnetic relay whereby a precisely wound coil structure may be utilized.

In carrying out my invention, in one form thereof, I apply it to an electromagnetic relay having an insulating housing formed by a plurality of cooperating members fastened together in complementary relationship. Within thishousing are arranged at least one pair of relatively movable contacts and a reciprocable magnetic armature for operating the contacts. The reciprocating movement of the armature is guided laterally by-an axially movable sleeve which transmits motion from the armature to the relay contacts through a spring to operate the contacts. An electric coil is attached to the housing for energizing the armature. The magnetic armature is slidable on the sleeve and energizable by the coil to move the sleeve between two positions for controlling the relay contacts. By my invention, the sleeve is constructed of a material having a relatively high melting point, and it also has an axially extensive split formed in it. An annular cap member is fastened to the sleevein a constricting relationship, with the'spring located between the armature andcap member. The split of the 'sleeve is partially closed by the cap member and stresses are imparted to the sleeve by the cap member, which secure these members together. The position of the cap member on the split sleeve is ad justed during the manufacture of the relay to compensate for variations in the operative characteristics among a multiplicity of mass produced relays. By forming the sleeve of this relay with an axially extensive split, and of a material having a relatively high melting point, an inexpensive and improved means is thereby provided for enabling the relay to efliciently carry a relatively high current. i

By a further aspect of my invention, I provide a T-shaped insulating member which serves as part of a relay housing and efficiently provides a bobbin for receiving a prewound coil during the assembly of the relay. This arrangement significantly enhances the efficiency of operation of the coil and also provides a simplified and low cost method for manufacturing the relay. Such structure and method for making the relay may, of course, be combined with the aforesaid relay arrangement to provide a particularly desirable device and manufacturing technique. 7

Further aspects of my invention will become apparent hereinafter, and the specification concludes with claims particularly pointing out and distinctly claiming the submay best be understood by reference to the following description when taken in conjunction with the accompanying drawing in which: i 2

FIG. 1 is a front view of an electromagnetic relay embodying my invention; 7

FIG. 2 is a front cross-sectional view taken through the center of the side of the relay of FIG. 1;

FIG. 3 is an exploded perspective view of the component parts of the relay of FIG. 1; and

FIG. 4 is an elevational view of the contact bridging assembly of the relay with the bridging contact member and armature shown in section to more clearly illustrate the sleeve.

Referring to the drawing, the invention is shown in one form embodied in a relay 1 of a calibrated current type used in split-phase starting of fractional horsepower motors. To enhance its manufacturability'and flexibility of application, relay 1 comprises a three-part insulatinghousing 3 formed by] complementary cooperation of upper, intermediate, and lower base or casing members 5, 7, and 9, respectively. The three base members 5, 7, and 9are stacked one upon the other and interfitted with each other, being securely held together to form the housing by means of shaft ll having head 13. The headed shaft 11 extends through aligned apertures 15, 17, and 19 of the housing members and is retained by a quickly attachable, push-on fastener 21.

The intermediate housing member 7 is generally T-shaped in configuration, including rectangular platform 23 and a generally cylindrical upright section 25. FIG. 3.) Upper member 5 has a generally rectangular box-shaped configuration. To enable intermediatememher 7 to be interfitted with upper member 5, the upper end 26 of member 7, as shown in FIG. 3, is curved, flattened and stepped at 27, 29, and 31, respectively. Upper end 26 of member 7 engages an appropriate recess formed in the bottom of member 5, with keying section 33 of member 7 entering keyway slot 35 of memberS, to provide a secure complementary interengagement of the two members.

For interfitting intermediate member 7 with bottom member 9 of the relay housing 3, a generally rectangular projection or plateau 37 is extended downwardly from the lower surface thereof, viewing FIG. 3. Bottom housing member 9 assumes the general shape of a rectangular open box. Opposite sides of projection 37, such as side 37ashown in FIG. 3, fit into cooperating recesses 39 formed in the elongated side walls 41 of member 9. In addition, depending ribs 43 (FIG. 2) are also formed on the lower surface of intermediate member 7. Ribs 43 fit snugly upon recessed upper end wall surfaces 45 of member 9 (FIG. 3) to provide further interfitting engagement of member 7 with member 9.

To support and contain the various parts of the relay, as shown in FIG. 2, housing 3 has an invertedT-shaped cavity 47 which includes horizontal chamber 49 and a vertical chamber 51 communicating with chamber 49. A movable armature and contact bridging sub-assembly 53 is slidably supported on vertical shaft 11 within chambers 49 and 51. The moving parts of sub-assembly 53 include a sleeve 55 axially slidable on shaft 11, a cylindrical magnetic armature member 5'7 vertically slidable on sleeve 55, and a contact bridging member 59 extending below armature member 57 within horizontal chamber 49. (See FIG. 2.) p v To provide a new and improved relay which will eiliciently carry a relatively high electrical current through contact bridging member 59, as shown in FIGS. 2 and 4,

(See

sleeve 55 is constructed from a metallic material having a relatively high melting point, such as the metal brass, and also has a split 61 formed therein. More particularly sleeve 55 has a generally cylindrical configuration, split 61 thereof being disposed in parallel relationship to the axis of the sleeve, to provide an axially extensive gap 63 of substantially uniform width (FIG. 4). The bottom of sleeve 55 has a collar 73 formed upon it, the purpose of which shall become apparent hereinafter.

For presetting and standardizing the operating characteristics of the relay 1, and thereby enhancing the manufacturability thereof, an annular metal cap 65 is adjustably mounted upon upper end 67 of sleeve 55 by peripherally constricting the sleeve to diminish gap 63 (at the level of cap 65). In specificity, the inner diam eter of cap 65 is such that the sleeve 55 is stressed thereby. (See FIG. 4.) Sleeve 55 thereupon tends to enlarge itself and to restore the original size of gap 63 by the exertion of radial pressure upon the cap 65. The radial pressure which is exerted upon cap 65 by sleeve 55 secures the two parts together. By means of the peripheral constriction imparted to the sleeve 55 by cap 65, a simplified and efficient means is thus achieved for adjustably securing cap 65 to sleeve 55 in various relative dispositions. By altering the relative dispositions of cap 65 and sleeve 55, as shall become apparent hereinafter, the operating calibration of relay 1 may be conveniently and accurately preset.

To transmit motion between armature member 57 and sleeve 55, a resilient means, such as light coil spring 69, surrounds sleeve 55 between armature member 57 and cap 65. Spring 69 allows the armature member 57 to vibrate under the influence of alternating excitation while substantially minimizing any chattering of the contacts.

Contact-bridging member 59 is a conductive metal strip loosely and slidably mounted on split sleeve 55 by the insertion of sleeve 55 through an aperture 71 (FIG. 4) in the center of the bridging member 59. Collar 73 on the bottom of sleeve 55 acts as a lower stop and supporting section for the bridging member 59, acting thereupon through metal spacer 74. Armature member 57 normally rests when in an unenergized condition on bridging member 59 (as shown in FIGS. 3 and 4) but is free to move upwardly on sleeve 55 away from the bridging member against the force of spring 69. Contact bridging member 59 carries movable contacts 75 at opposite ends which upon elevation of the bridging member 59 engage stationary contacts 77 carried by terminal members 7 9.

The terminal members 79 comprise an elongated strip of conductive metal having an internal rectangular section 7% which carries the stationary contact 77, and an external connecting section 7%. As shown in FIG. 3, opposing side edges 81 of the internal rectangular section 79a have inwardly stepped indentations 83 formed on the corners of contact end 85 and a pair of opposed recesses 86 formed near connecting section 7%. By means of stepped indentations 83, contact end 85 of terminal 79 fits snugly into stepped recesses 87 formed in the upper surfaces of one of the side walls 41 of member 9, near the outer ends thereof. More particularly, the stepped indentations 253 of terminals 79 generally engage oppositely disposed inner vertical corners 89 (FIG. 3)

of stepped recesses 87 to furnish a precise entrapping support for terminal contact ends 85 within housing 3. In the side wall 41 of bottom member 9 opposite to the side wall in which recesses 37 are located, a pair of open slots 91 are formed. The slots 91 are in alignment transversely with recesses 57 and are dimensioned to receive the section of terminal 79 which is disposed between each pair of terminal recesses 86. (See FIG. 3.) Recesses 86 of terminals 79 thus bracket the side walls of each of the slots 91 to provide a precise entrapping support for the other side of terminal section 79a within housing 3. The interengagement of indentations 83 and recesses 86 of terminals 79 with cooperating recesses 87 and open slots 91 of member 7, thus serves to securely trap the terminal members 79 within housing 3 against any forces tending to pull these terminal members out of the relay.

Turning now to a further explanation of the external aspects of relay housing 3, as shown in FIG. 3, the intermediate member 7 has the aforementioned upright section 25 formed upon it. Section 25 has a generally smooth cylindrical configuration between the lower stepped surfaces 31 and platform 23 to form a bobbin for accommodating an electrical coil 93. Coil 93 is prewound on an arbor and pretested before assembling it to section 25 of member 7. During the final assembly procedure, as shall be further set forth hereinafter, coil 93 is then dropped onto section 25 of member 7 before member 5 is placed thereupon. By using a prewound coil in cooperation with the T-shaped housing member 7, the diameter of spool section 25 may be readily coordinated with the size of wire used in the coil to obtain a more precisely wound coil. In addition, the spool section 25 may also be made of such a diameter that it does not have to withstand winding stresses such as are incident to a coil wound directly onto the spool section. (See FIG. 2.) Such a coil arrangement, therefore, significantly enhances the efficiency of operation as well as the manufacturability of relay 1.

In operation of relay 1 for starting a motor, when the motor is energized, an electric current in coil 93 produces a magnetic field which elevates magnetic armature 57 on split sleeve 55 (viewing FIG. 2) against the force of spring 69. The elevation of armature 57 is transmitted by spring 69 against cap 65, which in turn causes the elevation of sleeve 55 on shaft 11. As sleeve 55 moves upwardly, it carries contact bridging member 59 on collar 73 until movable contacts 75 engage the stationary contacts 77 on the terminal members 79, thereby making connection between conductors connected to these contactcarrying terminals 79. (See also FIG. 1.) It will be appreciated that adjustment of the vertical position of cap on split sleeve 55 during manufacture permits precise control over the point that contacts 75, 77 engage during elevation of armature 57 such that the magnetomotive force required to elevate each armature to its contact closing position can be made identical despite minor variations in the size and location of the contact bridging sub-assembly 53. Further elevation of magnetic armature 57 beyond its contact-kissing position increases the contact force transmitted to the contact bridging member through spring 69, cap 65 and slidable split sleeve 55. Spring 69 also prevents vibrations in the energized armature from being transferred to the contacts. The maximum elevation of magnetic armature 57 is limited by annular shoulder 94 in the intermediate housing member 7 As previously set forth, sleeve 55 is made of a metallic material such as brass, which has a relatively high melting point. Clt is also advantageous that this material be rigid in structure and have a good thermal conductivity. Because of the relatively high melting point of sleeve 55, when current flows through contact bridging member 59, sleeve 55 effectively and efficiently withstands its thermal association with the bnidging member 5 9 without incurring any deleterious effects. The thermal durability and stability of sleeve 55 is therefore considerably enhanced in comparison with prior art devices of an otherwise similar structure. In addition, split sleeve 55 serves to dissipate heat from the relay through shaft 11, and also breaks up induced current from coil 93 by acting like the open secondary' of a transformer to reduce eddy current flow and thereby lower the operating temperature of the coil. It will thus be understood that relay 1 may be efiiciently openated at relatively high currents. For example, such a relay may be operated at a terminal current of more than 28 amperes.

When the motor comes up to speed the current in coil may be reversed to their dotted positions.

113 for mounting the relay from the side.

7 occur at the contacts.

To simply and conveniently attach my improved relay 1 to a supporting structure, as shown in FIG. 3, a U- shaped bracket 95 has been provided. The bracket 95 is preferably of spring steel, and includes a bight section 97with suitable lanced apertures 99 formed therein for external attachment to an associated support. Arms 101a and 101b of bracket 95 extend perpendicularly from bight section 97 and are oppositely disposed relative to each other. Each of these arms has a rectangular slot 103 and a cutout step 105 disposed at the outer end of the arm as shown in FIG. 3. For attachment of bracket 95 to relay housing 3 from a wide'variety of positions, the upper and lower housing members 5 and 9 each have four pairs of adjacent and coplanar rectangular ears 107 and 109 formed on outer surfaces thereof. T wo pairs of the ears 107 and 109' are formed on the outer horizontal surfaces of each of the members 5 and 9 (near the end walls) and one pair of the ears is formed on each outer vertical surface of each member. Each pair of adjacent ears 107 and 109 is disposed opposite to another pair for attachment to and cooperation with the arms of bracket 95. For example, one pair of ears 107 and '10 9 may be seen on the right side of member 5 in FIG. 3, on

end wall 111 thereof. The ears 107 and 109 on end wall 111 are disposed opposite to an associated pair of ears (partially shown) on wall 113 of member 5. Bracket 95 may thus be readily attached from above to walls 111 and 113 of member 5 as suggested in FIG. 3, by placing ears 107 through slots 103 of the bracket arm-s and cutout steps 1050f the bracket arms in engagement with edges 109a and 1091) of ears 109. Arm 101a of the bracket is then secured to wall 113 and arm 10 1b is secured to wall '111. In the event that it is desirable to mount relay 1 to its support from the rear of the relay instead of from above, viewing FIG. 3,'arms 101a and 1011; of the bracket Arm 101a then fits conveniently into the dotted position against wall 111, as shown in FIG. 3, and armltllb fits against wall 113. In like manner, bracket 95 may also be attached to member 9 from two positions (i.e., from below or the rear of the relay).

'It should further be understood that one arm of bracket 95 may be attached to upper wall 115 of member 5 and the other arm attached to the bottom wall-117 of member 9 in the same manner as described for mounting the bracket 95 to member 5. In particular, arm 101b of bracket 95 may be fastened to the ears 107 and 109 formed on upper wall 115 near side wall 113, and arm 101a of the bracket may be fastened to the ears formed on lower wall 117 near side wall 113 (FIG. 2). Bight section 97 is then spaced from and parallel to side wall I By reversing the arms 101a and 10112 of bracket 95 on the ears of upper and lower walls 115 and 117 near side wall 113, bight section 97 may be located parallel to the rear of the relay near Wall 113. In like manner, the bracket 95 may be mounted to both of the members 5 and 9 on the right side of the relay so that bight section 97 is either parallel to side wall 111 for mounting the relay from that particular side or parallel to the rear of the relay near wall 111, for mounting the relay from that particular position. It will thus beseen that by means of the structure of bracket 95 and the location of the relay ears10 7 and 109, my improved relay 1 may be conveniently mounted to an appropriate support from a wide variety of positions.

In assembling my improved relay 1, I preferably employ sevenal sub assembly operations, followed by the main assembly procedure.

In the sub-assembly operations, a stationary terminal ing member 9 118 placedon shaft 11, as suggested by FIG.

3. TIhenthe contact bridging sub-assembly 53 is slipped onto shaft '11 and slid downwardly. Stationary terminal members 79 are then positioned on the upper edges of member 9. Next, the intermediate member 7 is stacked in interfitting engagement with bottom member 9 with the upper end of shaft 11 extending outwardly through the upper end of aperture 17. The prewound coil 93' is then dropped into position on upright section 25 of member 7. After assembling the coil 93, upper member '5 is stacked in interfitting engagement with intermediate housing member 7. Coil 93 is thus locked on member 7 by member 5. Fastener 21 is thereupon fitted in position on the upper and outer end of shaft 11 to securely hold together the various parts of relay 1 in accurately assembled relationship. The ends of coil 93, at that point, are connected to their appropriate terminals. The U- sh-aped mounting bracket 95 is then attached to the relay housing, as described hereinbefore. This completes the assembly operation for my improved relay 1.

. It will now therefore be seen that my improved relay is capable of efiicientlycarrying a relatively high current. It will be further understood that improved relay is economical to manufacture and constructed in such a' manner that it lends itself to a wide varietyof applications.

While in accordance with the patent statutes, I have described whatat present is considered to be the preferred embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from my inven tion, and I therefore aim in the following claims to cover all such equivalent variations as fall within the true spirit and scope of this invention. 9

What I claim as new and desire to secure by Letters Patent of the United States is: i

1. An electromagnetic 'relay comprising an insulating housing, at least one relatively movable contact means supported in said housing, an axially movable sleeve mountedin said housing and movable between two positions to actuate said contacts, a reciprocable magnetic armature slidably mounted upon said sleeve, an electrical coil engaged with and held by said housing to energize said armature, a cap member fastened around said, sleeve, and a spring engaged between the armature and the cap member for resiliently transmitting the reciprocating motion of said armature to said sleeve to move the sleeve between said positions to actuate said contacts, said sleeve being formed of a metallic material having arelatively high melting point and having an axially extensive split therein to reduce eddy currentflow and lower the operating temperature of said coil, said cap member being fastened tosaid sleeve by constriction of said split to provide a simplified adjustment therebetween.

2.'An electromagnetic relay comprising an insulating housing, a conductive bridging member supported in said housing and having movable contacts at opposite ends for engagement with associated stationary contacts, an axially movable sleeve extending through said bridging member, said sleeve having a collar at one end supporting said bridging member in said housing, and said sleeve being movable betweentwo positions, a reciprocable magnetic armature slidably engaged uponsaid sleeve, an electrical coil supported on the exterior of said housing to energize said armature, acap member fastened around said sleeve,

and a compression spring engaged between the armature and the cap member for resiliently transmitting the re.- ciprocating motion of said armature to said sleeve to move the sleeve between said positions, thereby to move said movable contacts on said supported bridging member into and out of engagement with associated stationary contacts, said sleeve being formed of a metallic material having a relatively high melting point and having an axially extensive split therein to reduce eddy current flow and lower the operating temperature of the coil, said cap member being fastened to said sleeve by constriction of said split to provide a simplified adjustment therebetween.

3. An electromagnetic relay comprising a plurality of cooperating members fastened together in interfitting relationship by a means including a shaft to form an insulating housing, a conductive bridging member in said housing and having movable contacts at opposite ends for engagement with associated stationary contacts, a cylindrical sleeve axially slidable on said shaft and extending through said bridging member, said sleeve having a collar at one end supporting said bridging member in said housing, and said sleeve being movable between two positions, a reciprocable magnetic armature slidably engaged upon said sleeve, an electrical coil mounted on the exterior of said housing to energize said armature, a cap member engaged around said sleeve, and a compression spring engaged between the armature and the cap member for resiliently transmitting the reciprocating motion of said armature to said sleeve to move the sleeve between said positions, thereby to move said movable contacts on said supported bridging member into and out of engagement with associated stationary contacts, said sleeve being formed of a metallic member having a relatively high melting point and having an axially extensive split therein to reduce eddy current flow and lower the operating temperature of the coil, said cap member being fastened to said sleeve by constriction of said split to provide a simplified adjustment therebetween.

4. An electromagnetic relay comprising first, second, and third interfitted members cooperating to define an insulating housing with communicating horizontal and vertical chambers, a headed shaft extending through said vertical chamber and partially through said horizontal chamber for fastening the housing members together, said first housing member having a box-shaped configuration and including a recess therein, a conductive bridging member supported in said recess and having movable contacts at opposite ends thereof for engagement with associated stationary contacts, said second housing member having a generally T-shaped configuration with a generally cylindrical upright leg and a pair of flat arms extending outwardly in opposite lateral directions from one end of said leg, the arms of said second member engaging said first member around the periphery of said recess and said second member extending over and closing the recess, the upright leg of said second member extending outwardly and away from said first member, a coil fitted around said upright leg to form a coil and bobbin combination, a cylindrical sleeve axially slidable on said shaft and extending through said bridging member, said sleeve having a collar at one end supporting said bridging member, said sleeve being movable between two positions, a reciprocable magnetic armature slidably engaged upon said sleeve, a cap member fastened around said sleeve, and a compression spring engaged between the armature and the cap member for resiliently transmitting the reciprocating motion of said armature to said sleeve to move the sleeve within said horizontal and vertical chambers between said two positions thereby to move said movable contacts on said supported bridging member into and out of engagement with associated stationary contacts, said sleeve being formed of a rigid metallic material having a relatively high melting point and having an axially extensive split therein to reduce eddy current flow and lower the operating temperature of the coil, said cap member being fastened to said sleeve by constriction of said split to provide a simplified adjustment therebetween.

5. An electromagnetic relay comprising an insulating housing formed of a plurality of cooperating members, one of said members having a generally T-shaped configuration with a generally cylindrical upright leg, a prewound coil fitted around said cylindrical leg thereby to provide a coil and bobbin combination, at least one pair of relatively movable contacts in said housing, a sleeve in said housing axially movable between two positions to actuate said contacts, a reciprocable magnetic armature slidably engaged upon said sleeve, a cap member fastened around said sleeve, and a compression spring engaged between the armature and the cap member for resiliently transmitting the reciprocating motion of said armature to said sleeve upon energization of said coil to move the sleeve between said positions to actuate said contacts, said sleeve being formed of a rigid metallic material having a relatively high melting point and having an axially extensive split therein to reduce eddy current flow and lower the operating temperature of the coil, said cap member being fastened to said sleeve by constriction of said split to provide a simplified adjustment therebetween.

6. In an electromagnetic relay, a housing formed of three stacked interfitting housing parts comprising a base member, an intermediate member including a spool section, and a cover member, said housing having an internal cavity, movable contact means supported in said cavity, stationary terminal means held between said base member and said intermediate member and extending into said cavity for cooperation with said movable contact means, means including an armature in said cavity for operating said contact means, a pre-wound coil for actuating said armature, said coil being fitted around said spool section of said intermediate housing member and trapped thereon by said cover member, and means for securing said housing members together.

7. The relay of claim 6 wherein the intermediate member has a T-shaped configuration, the upright section of which serves as said spool section for receiving the prewound coil.

8. The relay of claim 6 wherein at least one of said base and cover members has two pairs of coplanar rectangular ears formed respectively on two opposite outer walls of said member, the ears of one pair being across from the ears of the other pair, and a U-shaped bracket with opposed arms and a connecting section therebetween, the arms of said bracket each including a slot and a cutout step, the slot and step of each of said arms engaging one associated pair of said coplanar ears with the connecting section of said U-shaped bracket facing in a first direction thereby to attach said bracket to said one member from one position, the slot and step of each of said arms also being cooperable with said associated pair of said coplanar ears with said connecting section facing in a second direction located from said first direction thereby to attach said bracket to said one member from another position.

9. An electromagnetic relay comprising first, second, and third interfitted members cooperating to define an insulating housing with communicating horizontal and vertical chambers, said first member having a box-shaped configuration and including a recess therein, a conductive bridging member supported in said recess and having movable contacts at opposite ends for engagement with associated stationary contacts, said second member having a generally T-shaped configuration with a generally cylindrical upright leg and a pair of flat arms extending outwardly in opposite directions from one end of said leg, the arms of said second member engaging said first member around the periphery of said recess and said second member extending over and closing the recess, the upright leg of said second member extending outwardly and away from said first member, a precisely prewound coil fitted around said upright leg thereby to form a coil and bobbin Combination, a magnetic armature reciprocably mounted in said horizontal and vertical chambers, said armature being activated by said coil and operating said bridging member, the third housing member fitting on said second housing member after said coil has been fitted around said leg to secure the coil in position on the second member, and fastening means for securing said first, second, and third housing members together in complementary relationship.

10. An electromagnetic relay comprising an insulating housing, at least one relatively movable contact means supported in said, housing, an axially movable sleeve mounted in said housing and movable between two positions to actuate said contacts, a reciprocable magnetic armature slidably mounted upon said sleeve, an electrical coil mounted around a portion of said housing to energize said armature, a cap member mounted on said sleeve, and a spring engaged between the armature and the cap member for resiliently transmitting the reciprocating motion of said armature to said sleeve, said sleeve being formed of a metallic material having a relatively high melting point and having an axially extensive split therein to reduce eddy current flow and lower the operating temperature of said coil, and said cap member being mounted on said split sleeve at a selected location to adjust the spring force between said armature and said 10 sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 

1. AN ELECTROMAGNETIC RELAY COMPRISING AN INSULATING HOUSING, AT LEAST ONE RELATIVELY MOVABLE CONTACT MEANS SUPPORTED IN SAID HOUSING, AN AXIALLY MOVABLE SLEEVE MOUNTED IN SAID HOUSING AND MOVABLE BETWEEN TWO POSITIONS TO ACTUATE SAID CONTACTS, A RECIPROCABLE MAGNETIC ARMATURE SLIDABLY MOUNTED UPON SAID SLEEVE, AN ELECTRICAL COIL ENGAGED WITH AND HELD BY SAID HOUSING TO ENERGIZE SAID ARMATURE, A CAP MEMBER FASTENED AROUND SAID SLEEVE, AND A SPRING ENGAGED BETWEEN THE ARMATURE AND THE CAP MEMBER FOR RESILIENTLY TRANSMITTING THE RECIPROCATING MOTION OF SAID ARMATURE TO SAID SLEEVE TO MOVE THE SLEEVE BETWEEN SAID POSITIONS TO ACTUATE SAID CONTACTS, SAID SLEEVE BEING FORMED OF A METALLIC MATERIAL HAVING A RELATIVELY HIGH MELTING POINT AND HAVING AN AXIALLY EXTENSIVE SPLIT THEREIN TO REDUCE EDDY CURRENT FLOW AND LOWER THE OPERATING TEMPERATURE OF SAID COIL, SAID CAP MEMBER BEING FASTENED TO SAID SLEEVE BY CONSTRICTION OF SAID SPLIT TO PROVIDE A SIMPLIFIED ADJUSTMENT THEREBETWEEN. 